Use less when referring to a single item.
Use fewer when referring to more than one item.

Fewer or Less

Writers often misuse the words less and fewer. The word less should be used for a single item (e.g.,
less time, less space). The word fewer should be used when there is more than one item (e.g.,
fewer mice, fewer omissions).

Examples:

There is less cheese on this plate.

(The word cheese is singular.)

There are fewer pieces of cheese on this plate.

(The word pieces is plural.)

There are less pigeons in Trafalgar Square than there used to be.

(should be fewer pigeons)

In the future, there will be less coins in circulation.

(should be fewer coins)

Fewer people will vote in the forthcoming elections.

Select the correct version:

ADOPT THE RULING!

Many people consider this ruling outdated. It is certainly not well observed by some large reputable
companies. For example:

less bags
(fewer bags )
Asda (Wall*Mart) poster

less napkins
(fewer napkins )
Starbucks

less emissions
(fewer emissions )
Volvo

Grammar Monster advises that you play it safe and adopt the ruling. Using less incorrectly may irk your readers. Using fewer correctly will showcase your grammar skills.